Comminuting solid substances



June 18, 1929. w. OSTERMANN COMMINUTING SOLID SUBSTANCES Original Filed May 1924 INVENTOR Waller Oslermamz ATTCRNEY Patented J me ls, 1929. I

UNITED STATES PATENT OFFICE.

WALTER OSTERMANN,

assreuma Original application flied May application fil OF BARMEN-LANGERFE-LD, GERMANY, LSSIGNOR, BY MESNE NTS, TO INDUSTRIAL SPRAY DRYING" CORPORATION, OF NEW YORK, 'N. Y., A CORPORATION OF DELAWARE.

eommuu'rme SOLID soas'raucas.

6, 1924,, Serial No. 711,390, and in Germany May 18, 1923. Divided ed July 13, 1928. Serial No. 292,499.

means, and more particu 1011 of such materials to Heretofore when it was desired solid substances to a particularly small particle size, as for example, th the colloidal state, chemica ordinarily been resorted to.

l years, however,

mechanical means devised which have made possible tion of the particle size a fineness at 1 state of colloidal so of solid m larly to the reduca veryfine powder.

to reduce at represented by 1 treatment has In the last few have been the reducaterials to east closely approaching the lotion. These colloid mills so called, have provided a very notable advance in the opened up many new pli cation.

Colloid mill the finely comminuted sol of a liquid dispersion,

art of operation,

ments of colloid mill principles of ly involve,

speed and other features,

stantia-l quantity of a liquid vehicle,

the medium of action is applied.

inherent produ marked effectiveness 0 way of fine commlnutlon limited-up to where a liquid hi gli the use which the intense ction 0 As a consequence of f a liquid material, the f the colloid mill in the has been practically comminution and have fields of industrial ap-.

however, provides id only in the form for while the embodioperation they all essentialoperating of a subthrough disruptive this the present, to applications dispersion minu-ted solid is satisfactory.

It has been attemptediheretofore of the finely comto render the highly effective comminutionof 'the. colloid mill an available medium fort-he production of finely cemml state, but the complicated prescribed has served principally the colloid mill action,

lished the end sought;

the prior method of" comminuted, carried tity of a liquid vehicle ectrolytes designed to act as despersingiagents, and, in some 1! stances, containing protective colloids also, 1s introduced into a colloid mill ofthe crosse dies an .eccentrically 1y nullify satisfactorily accomp In accordance withtreatment, the solid tobe -in .a substantia containing cer beat-er. type, mounted rotor.

which embo modeof l-quan tain e1 Thebatch of'liqui nuted solids in the dry treatment to materialand has not d material able refloceulation and this .is then subjected to the high-speed mill action for several'hours to obtain suitable comminution of the solid. The batch operation of this type of mill is characterized, howe.ver, by a for the time necessary for not above one percent, most of the dispersed solid being present in a coarser condition.

Thereafter, the liquid dispersion must be subjected to a centrifuging operation to effect a separation of the coarse from the fine sus pended-particles in the mill-treated liquid. Finally, this centrifuged suspension of the fine particles isthen dried as a mass, frequently in vacuo, to eliminate the liquid vehicle. The quantity of fine suchprocedure is very small in proportion to the quantity of solid raw material used, and the. practical inefficiency of the operation is pronounced. The caking effect of the mass drying is particularly objectionable in that it serves to greatly nullify the fine comminution secured. in the mill; Furthermore, the numerous steps and prolonged period of handling involved, 'serve to enhance considerably powder obtainable by quantity of materials the possibility of undesirably refiocculation of i the finely comminutedjmaterial whichis dis- The very fine particles v Brownian movement, and unless protective colloids or similar means are used, consider- Will rapidly take place, rendering the comminuting effect of the mill proportionately valueless. Inaddition, the non-uniform and incomplete comminuting action of the crossed-beater mill, as well as the subsequent centrifugal separation of the d coarse particles with the attendant sweeping out of fine particles therewith, also contribute to the inefiiciency of the operation and the generally unsatisfactory nature of the re sults obtained.

It is an object of my invention to over-.

come these deficiencies of the prior art and to provide a method and apparatus for producing finely ,comminuted solid materials wherein the solid can be reduced to very small particle size through the medium of colloid mill action and then be obtained, in the dry state, in the form of Very fine powder.

According to my invention, the solid material, while contained in a suitable liquid, is first mechanically comminuted to the desired particle size by a colloid mill action, preferably one which effects such a substantial and sufiiciently uniform comminution as.

to obviate the necessity of using a centrifugal separator. I The resulting liquid dispersion of the very finely comminuted solid is then atomized into a fine fog or mist, in sufliciently prompt sequence to the completion of the comminuting and dispersing operation as to re- X duce to a minimum the possibility of objecfaces 10, 10'. in the working gap 7 is provided for by a. cir- 'cumferential :libledheating or cooling medium may be eircu- =ate. v i

. The mill per se is the subjectof my co.

tionable reflocculation and settling. The liquid dispersion is then dried while in such fine 1y atomized form,'whereby the solid material is obtained in finely comminuted'dry form.

An illustrative form of, apparatus embodying my invention is described in the Fig. 4 s" a cross-sectional detail on an en- .larged, scale showmg the cooperating surfaces of the mill of Figs. 1 and 2.

Referring to the drawings Rdesignates generally arotor member and S a stator member surrounding the rotor R, which members may be of slightly frusto-conieal form as .shown in' Fig. 1 or of cylindrical form as shown in Fig. 2. The cooperating surfaces 5 and 6 of the rotor and stator respectively are positioned in closely adjacent, but noncontacting relationship whereby a slight clearance or working gap 7 is provided therebetween, for the fine adjustment of which clearance the slightly conical construction in Fig.

lis particularly advantageous. .These surfaces 5 and 6 are provided respectively, with similar longitudinalgrooves 8,8 which may be straight or helical and of curved. or angular cross-section, and with longitudinal teeth 9, 9 which terminate in substantially flat Regulation of the temperature acket 11 through which a suitpending application, Serial No. 711,390, filed lay 6th, 1924, of which this application is a division.

As shown in Figs. 1 and 2 a charging chamber 12 is disposed at the feed end of the rotor R, into which chamber thematerials to be treated in the workin gap 7 are introduced through a tangentially disposed inlet pipe 13, and at the other end of the rotor,1a chamber 14 is provided from which the mill-treated materials are discharged through a tangentially disposed discharge pipe 15 (Fig. 3)

mounted at the side of the mill opposite the tangential inlet pipe 13.

Helical members 16 and 17, mounted on the rotor shaft 18, are disposed in the chambers 12 and 14 respectively in substantially spaced relationship to the surrounding casing wall, to aid the introduction and discharge of materials into and from the mill, and the feeding may be further facilitated by extending the walls of the chamber 12 in a somewhatbaflle plate 24 is disposed in partially"0b-.

structing relationship to the communicating passage between the chambers.

The operation of my invention is substantially as follows:

The solid material to be comminuted is prepared in suitably small particle size topermit its ready introduction into the narrow working gap 7 while contained in the liquid vehicle, and is preferably thoroughly mixed with and suspended in the liquid for example water, prior to its introduction into the mill. The liquid material, i. e. the resulting mixture of solid and liquid, is then introduced through the tangential inlet pipe 13 into the chamber 12 whence it is fed into the working gap 7 betweenthe rotor and stator. As best indicated by Fig. 4, thecooperating surfaces 5 and 6 are of such configuration and relative arrangement that when the rotor R is lyrotated at thehigh speed characteristic of my operation, the liquid material confined in the working gap 7 is subjected while in the form of a thin liquid film to an intense film shearing action between the opposed flatfaces 10, 10 of the teeth 9, 9, to a violentehurning bythe action of the cooperating grooves 8, 8' and to an intense film beating action by thev sides and edges of passingjteeth 9,9. The effect of these actions i'st'o produce a. remarkably fine comminution and uniform dispee isionof the solid materialin tl iej liquid.

The rotor R should be maintained at a speed of preferably not less than 3,000 revolutions per minute and at suchhigher R. P. M.

as is necessary to produce the degree. of comminution desired. The higher the rotor speed and the narrower the clearance between the rotor and stator the more intense is the coinminuting action to which the liquid material in the very narrow working gap is subjected.

With the cylindrical form of rotor, flow of the material through the mill will be mainly induced by the action of the helical members 16 and 17 and the suction effect of the high speed gas current at the outlet of discharge pipe 15. With the conical form these flowinducing factors will be supplemented by the pumping action induced by the increasing centrifugal force resulting from the gradual widening of the diameter of the rotor, which will tend to draw the material'- into and through the working gap. The impeller 16- and the expeller 17 find particularly effective application when very viscous material is being treated. j

Air or other suitable gas under considerable compression and preferably hot, is injected into the atomizing chamber 21 through the nozzle 22, and the mill-treated liquid material delivered to the chamber 14' after treatment in the working gap, is rapidly discharged. into the atomizing. chamber through the medium of the helical expeller 17, the tangential disposition of the. discharge pipe 15, and the suction created by the gas current. When the mass of liquid material proceeding from the discharge pipe 15 meets this opposing high speed current V of gas, it will be violently dispersed into minute particles or droplets, and these particles will be propelled at high velocity in the direction of the drying chamber 23.

Upon reaching the drying chamber the par ticles will be subjected to an intense impact. against the baffle plate 24. disposed in their path, as a result ofwhich they will be further shattered into more minute particles or droplet's'an d' diverted downwardly as a fine fogor mist into the drying chamber proper. 5o

These *minute particlesof liquid material constituting the fine mist are dried while in gaseous suspension ln-the drying chamber 23 and the drying gas and heat may be'supplied through the medium of the atomizing gas, and or separately in the drying cham-- her, or otherwise as-may be apparent to one skilled in the art. Thefine, dry powder of thesolid material which results may be sepsents many advantages arated from the gas and collected in any well known manner. e e

By the application of my invention a com- "minution results which. is unattainable by prior comminutingpractice, and arapid and continuous operation. isprovided which preover the prolonged and relatively ineffective batch treatment of the prior practice.

The action of the mill is particularly effective and thorough, and results in such a uniform and fine comminution and disperl0 sion of the solid in the liquid, that no practical necessity exists for separating coarse particles by a centrifuging operation, prior to drying the suspension. This elimination of the centrifuging step avoids the loss of fine material as well as undesirable prolongation of the operating period. 'By subjecting the liquid mill-treated material to the continued dispersive'action of the subsequent atomization, in sufficiently rapid sequence to the comp'letionof the milling operation as to reduce to a minimum the possibility of objectionable reflocculation and settling, and drying it while in atomized form,

the-refiocculation factor is practically elimition of very finely comminuted solid ma- 90.

quence to the comminuting and dispersing operation in the mill, a high yield of fine powder may be obtained without the use of protective colloids or similar means as is the preferred manner of operation, a result impossible of attainment by the prior practice. If it'is desired to use protective colloids and the like in the application of my novel operation, a high yield of finely comminuted, uncaked powder may be obtained, which alsov is impossible of production by the procedure used heretofore.

My invention is capable furthermore of widespread application. Not only is it advantageously applicable for the fine comminution of' a smgle substance, but maybe usedto particular advantage for securing a homogeneous solidniixturc of a plurality of finely comminuted substances, and insuch other applications as will be apparent to one skilled in the art. I A

Obviously the solid materials'which may be subjected totreat-m'ent according to' my invention comprise not only strictly solid Y materials, but also such semi-solid and liq-- uid materials, for. example, melted solids, as are capable of being obtained in non-fluid form. This-general category ofsubstances and mixtures thereof are to be considered as coming within the scope of the term solid appearing in the claims I claim as my invention: 1. The method of producing finely comminuted solid material which comprises subjecting the solid material while carried in afilm of liquid to iigh speed mechanical com- 2. The method of producing finely comminuted solid material which comprises mechanically comminuting and dispersing the solid material at a high speed while carried in a film of liquid, whereby a fine dispersion of the solid in the liquid is obtained, con acting the resulting liquid material withKan atomizing current of gas, and drying the 'esulting dispersed liquid particles while suspended in drying gas. I

3. The method of producing finely comminuted solid material which comprises mechanically comminuting and dispersing the solid material at a high speed while carried in a film of liquid, atomizing the resulting liquid material and imparting a high velocity to the'particles so obtained, subjecting the moving particles to a further atomizing impact, and drying the particles while suspended in drying gas.

4. The method of producing finely comminuted solid material which comprises subjecting a film of liquid containing the solidmaterial to a high speed film shearing action to obtain a dispersion of said material in Hue ly comminuted form, then atomizing the resulting liquid material, and then drying the atomized material in gaseous suspension to obtain a fine powder.

5. The method of producing finely oomminuted solid material which comprises subjecting a film of liquid containing the solid material to a high speed shearing, beating, and churning, whereby said material is finely comminuted and dispersed, then atomizing the resulting liquid material to reduce it to small particles, and then drying said particles to obtain a fine powder.,.

6. The method of producing finely comminuted" solid material which comprises, attenuating a liquid containing the solid to be comminuted to the form of a thin film and subjecting said film while in a confined space to a hlgh speed shearing, beatlng and churnmg action whereby a fine dispersion of the solid in the liquid is obtained, then atomizing niikture into the form of a thin liquid film containing the solid particles and shearing,

the liquid dispersion into minute droplets in suffic'ently rapid sequence to the completion of the aforementioned operation to avoid material reflocculation of the dispersed solid, and drying said droplets While in gaseous suspension to obtain a' fine powder of the solid material; 1

I jecting the-solid to be comminuted while car- 7. The method of producing finely com v minuted solid material which comprises, sub- I. ried in a thin film of liquid to the comminuting forces set up in a film of. liquid when confined between closely adj acent, non-contacting-surfacesrelatively movingatvery high speed, whereby a fine dispersion, of the solid in the liquid is obtained, then atomizing the 8. The method of producing finely comminuted solid material which comprises sub jecting a thin film of liquid containing-the solid material to be comminuted, to the comminuting forces set up in a film of liquid when confined between closely adjacent, noncontacting concentric surfaces relatively rotating at very high speed, whereby a fine dis persion of the solid in the liquid is obtained, then atomizing the resulting fine liquid dispersion into minute droplets, and drying the droplets to obtain a fine powder of the solid material.

9. The method of producing finely com minuted solid material which comprises, subjecting a thin film of liquid containing the solid material to be comminuted, to the comminuting forces set up in a film of liquid 10. The method of producing finely comminuted solid material which comprises, subj ecting the solid to be comminuted while contained in a thin film of liquid to the comminuting forces set up in a film of liquid when confined between closely adjacent, non-con.- tacting surfaces relatively moving at high speed, whereby a fine dispersion of the solid in the liquid is obtained, then contacting said fine liquid dispersion with a current of gas moving at high velocity to atomize the dispersion into a fine mist, and then drying said mist with drying gas to obtain a fine powder of the solid material.

11.7 The method of.producing finely comminuted' solid material which comprises, mixivng the solid to be comminuted with a substantial quantity of liquid, attenuating the liquid beating, and agitating said film at high speed, whereby the solid is finely comminuted and dispersed in the liquid, then atomizing -said drying said droplets to remove the liquid and obtain'a fine powder of the solid material.

12. A method of disintegrating particles suspended in a liquid comprising, subjecting a verythin film of the liquid with the suspendliquid'disp'ersion intominute droplets, and

ed particles therein to the action of closely ad- I j acent surfaces relatively moving one past the other: high velocity, the particles being disthe increase of the relative velocity of the sursurfaces, and decrease with space is integrated by reason faces, and decrease with theincrease in the thickness of the film, and atomizing the material so treated by a current of gas whereby the pressure on the material leaving the film also reduced.

13. A method of disintegrating particles suspended in a liquid comprising, subjecting a very thin film of the liquid with the suspended particles therein to the action of closely adjacent surfaces relatively moving one past the other at high velocity, the particles in their passage through the film being disof the disruptive forces within the film itself, which increase with the increase of the relative velocity of the the increase in the thickness of the film, applying pressure to the liquid that is entering the film space,

and atomizing the material so treated by a current of gas whereby the pressure on the material leaving the film space is also reduced.

'14. A method of disintegrating particles suspended in a liquid comprising, subjecting a very thin film of the liquid with the suspended particles therein to the action of closely adjacent concentric surfaces relatively rotating one past the other at high velocity, the particles being disintegrated by reason of the disruptive forces set up within the film during the relative rotation of the confining surfaces at high velocity and atomizing the material so treated by a current of gas whereby t-hepressure on the material leavingthe film space is also reduced. I

15. An apparatus for the comminution of solid material which comprises the combination of a mill having members provided with closely adjacent, non-contacting, co-operating surfaces relatively movable at a high speed between which the solid material is subjected in-a film of liquid to an intensive and a dryer for receiving the liquid mill-treated material having means for dispersing said liqui material into small particles, and means for,

drying said particles, whereby finely comminuted solid material is obtained.

16. An apparatus for obtaining solid material in finely comminuted form which comprises the combination of a mill having members provided with closely adjacent, noncontacting, co-o'perating surfaces relatively movable at a high speed between which the solid material is subjected in the presence of liquid to an intensive comminuting and dispersing action, means for atomizing the m1lltreated liquid material whereby continued dispersive action is secured, and a drying chamber associated with said last named means for receiving said atomized liquid material and for dryin thesame while in atomized form, where y finely comminuted solid material is obtained.

17. An apparatus for the comminution of solid material which comprises the combination of a mill having members provided with closely adjacent, non-contacting concentric surfaces of revolution relatively movable at a high speed between which the solid material is subjected in a film of liquid to an intensive comminuting and dispersing action, means for discharging the mill-treated liquid material from said mill, means for directing a current of gas moving at high velocity against said discharged material whereby said material is atomized and a high velocity is imparted to the resulting particles in the direction of movement of said gas, and a drying chamber disposed in the path of said gas for receiving and drying said particles while in gaseous suspension.

18. An apparatus'for treating solid material which comprises the combination of a mill having members provided with closely adjacent, non-contacting, cooperating surfaces relatively movable at a high speed between which the solid ed in a film of liquid to an intensive comminuting and dispersing action, a discharge pipe for said mill, an atomizing chamber associated with said mill in which saiddischarge pipe terminates, high speed current ofv gas through said chamber, means for causing the liquid mill-treated material to flow through said discharge pipe and into the path of the gas in said chamber,

whereby the mill-treated material is atomized by said gas and propelled co-currently therewith, and a drying chamber associated with said atomizing chamber for receiving the atomized particles and said gas wherein the particles are dried while in gaseous suspension.

'19." An appa atus for the production of a finely comminuted, homogeneous mixture of a plurality of solid substances which comprises the combination of a mill having members provided with closely adjacent, non-contacting, cooperating faces adapted to jointly contact with an extensive surface of a film of liquid confined therebetween containing the substances adapted to move relatively at very high velocity so that the particles of the liquid material so confined are subjected to intensive comminuting and dispersing action; and a drying chamber. associated with said mill, means for supplying a drying gas to said chamber, means for atomizing said mill-treated liquid material to disperse the same into a fine mist, and means for continuously introducing sai mist into thedrying chamber to subject said mist to the.act1on of said drying gas, wheremeans. for passing .a.

to be treated, said members being material is subjectwhile in said gaseous suspension and a finely comminuted, homogeneous mixture of the solid substances is obtained. 1

20. An apparatus for the fine eomminution of ,solid material which comprises, means for subjecting a film of liquid containing the solid material to a high speed film shearing, heating and agitating, whereby a fine dispersion of the solid in the liquid is obtained, means for atomizing said liquid dispersion into minute droplets, and means for drying said droplets to obtain a fine powder of the solid material. 21. An apparatus for the fine eomminution of solid material which comprises, means for attenuating to a film a liquid containing the solid to be comminuted and shearing, beating and agitating said film containing the solid 'at a high speed, whereby a fine dispersion of the solid in the liquid is obtained, means for atomizing said liquid dispersion into minute droplets, and means for drying said droplets while in gaseous suspension to obtain a fine powder of the solid material.

22. An apparatus for the fine comminution of solid material which comprises a generally cylindrical stator surface having alternate grooves and flat-faced teeth extending generally longitudinally thereof, a generally cylindrical rotor surface rotatable at high speed disposed in closely adjacent, non-contacting, concentric relationship with said stator surface and having similar grooves and teeth, means for introducing a liquid containing the solid material to be comminuted into the narrow gap between said surfaces wherein the solid material is finely comminuted and dispersed in the film of liquid by forces set up upon and in the film by the high speed rotation of said rotor, means for atomizing the liquid mill-treated material into minute droplets, means for conveying the milltreated material to said atomizing means, and means for drying said droplets while in gaseous suspension to obtain a fine powder of the solid material. s

23. An apparatus for the fine eomminution of solid material which comprises, a mill hav ing a pair of closely adjacent, non-contacting,

cooperating surfaces, each provided with alternate teeth and grooves, and relatively movable at high speed, between'whieh sur- 24:. An apparatus for the fine eomminution of sglid material which comprises, a mill having a frusto-conical stator surface provided with alternating shallow grooves and fiatfaced teeth extending longitudinally thereof,

a frusto-conical rotor surface rotatable at high speed and-provided with similar teeth and grooves, disposed in closely adjacent,

non-contacting, concentric relationship with said stator surface, means for conducting a liquid containing the solid to be comminuted into the narrow gap between said surfaces wherein the particles of solid are subjected while in a film of liquid to an intensive comminuting and dispersing action, means for atomizing the liquid dispersion so obtained into minute droplets, means for conducting the dispersion to said atomizing means, and

a driving chamber provided with hot drying gas for receiving the atomized dispersion and drying the droplets while suspended in said gasl to obtain a fine powder of the solid mater1a 25. In an apparatus for the fine comminution of solid material, the combination which comprises, amill having cooperating, comminuting surfaces relatively movable at high velocity, between which the solid material is finely comminuted and dispersed while contained in a film of liquid, an atomizing chamber connected with said mill for the reception of mill-treated liquid dispersion, means for passing a high-speed current of drying gas through said chamber, means for conducting said liquid dispersion into the path of said gas whereby the dispersionis atomized and propelled co-currently with said gas, and a drying chamber for receiving the gas carrying the atomized dispersion and drying the same while in suspension to obtain a fine powder of the solid material.- z y I In testimony whereof I affix my signature,

0 7, WALTER OSTERMANN. 

